Emission characteristics and environmental impacts of carbonyl compounds from construction machinery in China

Carbonyl compounds play a significant role in atmospheric chemistry, leading to the formation of ozone and secondary organic aerosols. Emissions of carbonyl compounds from construction machinery cannot be ignored. In this study, a total of 37 units of in-use construction machinery were tested using portable emission measurement system under real-world operating conditions. Carbonyl compounds were collected using the O-(2,3,4,5,6-pentafluorobenzyl) hydroxylamine derivatization method and analyzed via gas chromatography-mass spectrometry. The composite carbonyl compound emission factors of excavators, forklifts, loaders, road rollers, pile engines and graders were 3.30 ± 1.45 g/kg-fuel, 2.05 ± 0.97 g/kg-fuel, 3.20 ± 1.18 g/kg-fuel, 2.69 ± 1.02 g/kg-fuel, 5.55 ± 2.26 g/kg-fuel and 2.94 ± 1.31 g/kg-fuel, respectively. Pile engines exhibited the highest emission factors during working, whereas the others had the highest emission factors while idling. In addition, the continuous tightening of emission standards has effectively reduced the emissions of carbonyl compounds from construction machinery. The total emissions of carbonyl compounds from five typical construction machinery in China in 2019 were estimated to be 12.1 kt, with corresponding ozone formation potential (OFP) and secondary organic aerosol formation potential (SOAFP) of 82.5 kt and 360.1 t, respectively. Acetaldehyde and formaldehyde were the primary contributors to the total emissions and OFP, while benzaldehyde was the largest contributor to the SOAFP. The contributions of Jiangsu and Zhejiang provinces to total emissions of carbonyl compounds and their corresponding OFP and SOA were much higher than those of other provinces. Our results supplement the limited emission factor data for carbonyl compounds from construction machinery and can aid in improving emission inventories and developing targeted control strategies to enhance air quality.